docs: def datetime_to_http_date(the_datetime):
      """
      >>> datetime_to_http_date(datetime.datetime(2013, 12, 26, 9, 50, 10))
      'Thu, 26 Dec 2013 09:50:10 GMT'
  
      # Verify inverses
      >>> x = 'Thu, 26 Dec 2013 09:50:10 GMT'
      >>> datetime_to_http_date(http_date_to_datetime(x)) == x
      True
      """
      timeval = calendar.timegm(the_datetime.utctimetuple())
      return formatdate(timeval=timeval,
                        localtime=False,
                        usegmt=True)